Compositions and methods to detect illicit uses of fertilizers

ABSTRACT

Fertilizers may include one or more additives that render the fertilizer more resistant to further processing such as thermal processing and/or aqueous-based processing that may otherwise be employed in the attempt to produce explosive materials from the fertilizer. The one or more additives may include materials that increase the chances of detection by providing a visual or olfactory indication of further processing. The one or more additives may include materials that make further processing more difficult or dangerous.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Provisional Application No.61/372,698, entitled “ADDITIVES TO DETER ILLICIT USE OF FERTILIZERS,”filed Aug. 11, 2010; Provisional Application No. 61/372,651, entitled“METHODS FOR ADDING TRACERS TO FERTILIZERS,” filed Aug. 11, 2010; andProvisional Application No. 61/372,668, entitled “ADDITIVES FORDETECTION OF ILLICIT USE OF FERTILIZERS,” filed Aug. 11, 2010, each ofwhich are herein incorporated by reference in their entirety.

TECHNICAL FIELD

The present technology relates to fertilizers, such as ammonium nitratecontaining fertilizers. More particularly, the present technologyrelates to additives that can included in fertilizers to deter orinterfere with further processing of the fertilizers to produceexplosive devices.

BACKGROUND

It is well known that, because of its high concentration of nitrateions, ammonium nitrate has important uses in the field of agriculture ingeneral and fertilization in particular. However, in many of the formsin which it ammonium nitrate fertilizers are commonly used, it isrelatively difficult and potentially hazardous to handle commercially inlarge amounts, and/or to store in great masses (such as occur incommercial warehouses and storage bins), especially for relatively longperiods of time. Furthermore, certain forms of ammonium nitrate maydetonate under certain conditions, and have therefore sometimes beenillicitly used as an explosive material.

Many fertilizer products require additional processing in order torender them useful in an explosive device. For example, fertilizers canbe processed to enrich or separate the ammonium nitrate content bychemical purification methods. Such processing can include, for example,thermal processing and aqueous-based processing.

SUMMARY

Fertilizers according to embodiments of the present invention includeone or more additives that deter further processing of the fertilizerinto an explosive device. In one embodiment, the additives render thefertilizers resistant to further processing such as thermal processingand/or aqueous-based processing that may otherwise be employed in theattempt to produce explosive materials from the fertilizer. In anotherembodiment, the one or more additives increase the chances of detectionof further processing by providing a visual or olfactory indicationduring processing. Methods of forming fertilizers that include suchadditives are also disclosed.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the descriptionis to be regarded as illustrative in nature and not restrictive.

DETAILED DESCRIPTION

Fertilizers according to embodiments of the present invention includeone or more additives that render further processing more detectable.Fertilizers according to other embodiments may include one or moreadditives that deter, complicate or inactivate further processing of thefertilizer to produce explosive components. Additive combinations mayalso be employed.

Fertilizers containing nitrates, ammonium, urea and other knownfertilizing compounds can be further processed via any one of a numberof routes for producing illicit explosive materials. One such processingroute utilizes thermal processing at temperatures in excess of about 50or 60 degrees Celsius. Another processing route utilizes chemicalprocessing, which may include at least one aqueous processing step.Accordingly, in one embodiment, the fertilizer includes an additive thatactivates under the thermal processing, aqueous processing or both. Inanother embodiment the fertilizer includes a combination of additivesthat activate under either processing condition.

Components to Detect Further Processing

In some embodiments, fertilizers may include one or more additives thatfacilitate the identification of illicit activities such as processingfertilizers to make explosive devices, including, for example,improvised explosive devices (IEDs). These additives may be any suitablematerial, and can be selected to provide any desired property that canbe identified by security personnel. For example, the additive mayinclude a thermal decomposition or reaction product of the additive thatmay emitted from the fertilizer when the fertilizer is heated in afurther processing step.

In some instances, the additive or thermal decomposition or reactionproduct thereof may be selected such that it is emitted at a temperaturethat is above that of any expected storage conditions yet is withintemperatures that would be expected to be encountered during furtherprocessing steps. In some embodiments, the additive is selected suchthat is emitted or reacts at a temperature at or above about 50 or 60degrees Celsius. While a single additive may be referred to forsimplicity, it will be appreciated that any number of additives, eitherhaving similar or dissimilar detection and/or deterrent functionality,may be used.

In some embodiments, the additive may have a pyrotechnic effect duringthermal processing. For example, the additive may be a pyrotechnic“star” containing components known to produce an intense light whenignited. Suitable compounds include phosphorous, strontium carbonate,lithium carbonate, lithium chloride, calcium chloride, sodium nitrate,barium chloride, copper chloride, cesium nitrate, potassium nitrate,rubidium nitrate, charcoal, iron, lampblack, titanium, aluminum,beryllium, magnesium and combinations thereof.

In some embodiments, the additive may produce a colored smoke or vaporwhen the fertilizer is heated, thereby providing an indication to lawenforcement that someone is attempting to further process thefertilizer. Examples of additives that can produce a colored orotherwise visible smoke or vapor include “smoke bombs,” which include anoxidizer such as potassium chlorate, a fuel such as sugar a moderantsuch as sodium bicarbonate and a powdered organic dye.

In some embodiments, the additive may produce a distinctive odor thatcan easily be detected by humans when the fertilizer is heated orprocessed under aqueous conditions. Examples of suitable odorousadditives include organic thiols or mercaptans. These materials may,when contacted with water, react and decompose to release hydrogensulfide gas. Hydrogen sulfide gas is highly odorous and is easilydetected by humans. Other examples include nitrogen-bearing compoundssuch as pyridines and pyroles. These materials may, when contacted withwater, react to provide gaseous products having a distinctive fish-likeodor.

Further embodiments include certain linear carboxylic acids or otherhigher molecular weight acids, which are distinctly malodorous.Illustrative examples of malodorous linear carboxylic acids includeacetic acid (vinegar smell) and butanoic acid (rancid butter smell).Lower molecular weight acids such as butyric acid and valeric acid areheavy liquids that can be encapsulated. Certain higher molecular weightacids that are powders at ambient temperature but can dissolve andevolve odorous gases when contacted with water may also be suitable.

In some embodiments, if an ASN fertilizer is being subjected to anaqueous processing step, an ammonium/acid ion combination is formed. Theaddition of a sufficiently strong base can cause malodorous ammonia gasto be released as the base is dissolved. A suitable base is limestone,which can be mixed in with the dry fertilizer in a granular form. Insome embodiments, a milder base may be used if a metal chloride compound(such as iron chloride) is present. In some embodiments, using a plainmetal chloride can cause HCl gas to be evolved.

In some embodiments, the additive may provide a less-noticeable, orcovert, indication that the fertilizer is being heated or is otherwisebeing subjected to further processing. The additive or thermaldecomposition or reaction product thereof may not be emitted at aconcentration that is detectable by humans, but may be detectable by anelectronic detector or by a dog. Examples of additives that may not beovertly detected by humans but may be detectable by dogs includepheromones. In some embodiments, the pheromones may be encapsulated in awater-soluble coating that will dissolve upon aqueous processing. Otherexamples of relatively covert detection additives include those that mayfluoresce in specific types of light such as ultraviolet light, oradditives can be an identifiable compound that can be detected throughanalysis of the air or of an article that has been exposed to theadditive.

In some embodiments, the fertilizer may include a component that may bedetectable absent any further processing. In some embodiments, thefertilizer may include an easily detectable component that may providean indication that the fertilizer is in an unexpected location. Forexample, one would not be surprised or alarmed to discover fertilizer ina farmer's barn. However, finding a large quantity of fertilizer insomeone's urban garage may be an indication of illicit use.

In some embodiments, the fertilizer may include a component such as thedetection chemicals that are frequently added to commercially availableexplosives so that bomb-sniffing dogs can detect the explosives. Anexample of an additive that may be detected at low concentrations bydogs or by electronic detectors include t-butyl mercaptan, which iscommonly added to natural gas (which is otherwise odorless) for leakdetection. While a large cache of fertilizer may masquerade as a naturalgas leak, the resulting law enforcement investigation would likelyuncover the fertilizer.

In some embodiments, the emitted additive or thermal decomposition orreaction product thereof, can drift in the air and be detectable bysecurity personnel. In some embodiments, it can interact with the skinand/or clothing of people in the vicinity. For example, a colored vapormay cause staining of clothes or skin, or both. An odorous additive caninteract with or cling to clothing, or skin, or both.

In certain embodiments, the fertilizer includes at one thermallyactivated additive and at least one additive activated or release underaqueous conditions. For example, the fertilizer may include at least onepyrotechnic or smoke producing additive and at least one odorousmaterial.

Components to Deter Further Processing

In some embodiments, fertilizers may include one or more additives thatdeter the further processing of fertilizers in making explosive devices,including, for example, improvised explosive devices (IEDs). Additivescan be any suitable additive that can interfere with processing of afertilizer product. For example, additives can induce a thermal reactionwhen the fertilizer is processed, such as being subjected to apurification or chemical separation process, which can include heatingthe fertilizer.

In some embodiments, the additive may be selected to reduce thestability of the ammonium nitrate in the fertilizer. Illustrative butnon-limiting examples of suitable additives include halides, transitionmetal ions and combinations thereof. Examples of halides includefluorides, chlorides, bromides and iodides. Examples of transitionmetals include in particular zinc and copper. These materials can beadded applied to the fertilizer either during the fertilizermanufacturing process, or post-manufacture.

In certain embodiments, the fertilizer includes at least one detectableadditive and at least one deterrent additive. For example, thefertilizer may include at least one pyrotechnic, smoke producing or odorproducing material and at least one deterrent such as a transition metalion.

In some embodiments, urea may be illicitly processed in an attempt tomake an explosive material. If one is attempting to form urea nitrate,the amine functionality on the urea molecule is protonated by treatingwith concentrated nitric acid. If one is attempting to form nitrourea,the urea is protonated with concentrated sulfuric acid, followed bycontacting with concentrated nitric acid. In either event, strong acidprotonation is a step that may be exploited in designing a deterrent tothese reaction paths.

In some embodiments, the strong acid protonation step could be made moredifficult by including a basic material. In some embodiments, a materialcan be added that will react with the strong acids to form undesirablematerials or even provide an undesired (by the illicit processor) thatis sufficiently exothermic to cause a fire.

Fertilizers

A wide variety of fertilizers may be used with the additives of thepresent invention. Illustrative but non-limiting examples of fertilizersthat may be used include compounds containing nitrate groups, ammoniumgroups and urea groups. Examples of nitrate fertilizers include but arenot limited to ammonium nitrate, ammonium sulfate nitrate, calciumnitrate, potassium nitrate, sodium nitrate, and calcium ammoniumnitrate. Examples of ammonium fertilizers that do not contain nitrategroups include ammonium sulfate and ammonium phosphate. Due to the knowndetonation capabilities of ammonium nitrate, fertilizers that includeammonium nitrate or derivatives thereof are of particular importance.Examples include calcium ammonium nitrate and ammonium nitrate/ammoniumphosphate mixtures such as those described in U.S. Pat. No. 3,366,468,which is incorporated by reference herein in its entirety. Anotherexample of an ammonium nitrate (“AN”) fertilizer is ammonium sulfatenitrate. Although more processing is required, ammonium and ureafertilizers (or other fertilizers) that do not contain nitrate groups intheir intended form can be chemically converted to include nitrates.

In some embodiments, AN fertilizers may be provided primarily in theform of an ammonium nitrate double salt. As used herein, the term“double salt” is refers to a salt made up of at least two differenttypes of cations and one type of anion or of at least two differenttypes of anions and one type of cation. Thus, the term “double salt ofammonium nitrate” is understood to mean a combination of ammoniumnitrate and another compound in such a way as to form new compound whosecrystalline structure is distinct from the either of the constituents.

In some embodiments, an ammonium nitrate double salt may includeammonium nitrate and at least a second compound, said second compoundbeing present under conditions and in amounts effective to substantiallyreduce the detonation sensitivity of the composition and/or to otherwiseimprove a desired property of the composition. In some embodiments, thesecond compound is one or more of ammonium sulfate, ammonium phosphate,calcium nitrate, potassium nitrate, magnesium nitrate, ammoniummolybdenate, ammonium hexafluoralsilicate, neodymium hydroxynitrate, orcombinations of two or more of these. In some embodiments, at least asubstantial portion of the ammonium nitrate in the composition is in theform of a double salt with one or more of said second compounds.

In some embodiments the compositions, including the fertilizers andother materials of the present invention, have a relatively lowconcentration of single salt AN. As used herein the term “single AN”refers to a salt in which substantially all of the cations are ammoniumand substantially all of the anions are nitrate. In some embodiments thecompositions and materials of the present invention have no substantialamount of single salt AN, and in certain embodiments the compositionscontain not more than trace amounts of single salt AN.

In some embodiments, the present compositions, particularly in the formof fertilizers and when used in connection with methods involvinghandling the fertilizers, are not considered hazardous materials underTitle 49 of the Code of Federal Regulations, “Transportation”, Part 172,“Hazardous Materials Table”, Oct. 1, 2000, and are also preferably notclassified as oxidizers under United Nations Recommendations on theTransport of Dangerous Goods, Manual of Tests and Criteria, 1995”,“Section 34, Classification Procedures, Test Methods and CriteriaRelating to Oxidizing Substances of Division 5.1”.

In some embodiments, the double salts may be of the formula (I):(M)n(NH₄NO₃)m(H₂O)(I),where M is a cation-anion pair such as ammonium phosphate, calciumnitrate, potassium nitrate, magnesium nitrate, ammonium molybdenate,ammonium hexafluoralsilicate or neodymium hydroxynitrate, n is fromabout 0.2 to about 3, and m is from about 0 to about 10. Ammoniumsulfate nitrate (ASN) is an exemplary double salt. Further informationpertaining to these double salts may be found in U.S. Patent PublicationNo. 2007/0199357, which is incorporated by reference herein in itsentirety. Further illustrative examples of double salts, their formationand their properties may be found in U.S. Pat. No. 6,689,181, which isincorporated by reference herein in its entirety.

Although the AN double salts described herein are substantially morestable than their single salt counterparts, it is still possible throughthermal processing or purification techniques to form illicit materialsfor use in explosive devices. Accordingly, in one embodiment, afertilizer composition of the present invention includes at least one ANdouble salt such as an ASN double salt and at least one additivedescribed herein. In another embodiment, the fertilizer compositionincludes at least about 60 wt % of an AN double salt and at least oneadditive.

Manufacturing Process

The fertilizers of the present invention can be manufactured by anysuitable process to form liquid or solid fertilizers. For example, solidfertilizers may be formed by known granulation or prilling techniques.The additives may be added to the fertilizers in any number of wayseither during the fertilizer manufacturing process, or post-manufacture,including by direct mixing, discrete encapsulation and bycoating/soaking of fertilizer particulates.

When the additives are added during the fertilizer manufacturing processthey are a component of the manufactured fertilizer product. Additivescan be added at any suitable point during the manufacturing process. Forexample, the additive can be added to a liquid melt prior to the liquidmelt being provided to a prilling tower. Additives can be added duringthe fertilizer manufacturing process in any suitable manner, including,for example, addition of a additive as a stand-alone component, oraddition of a additive in an additive mixture that includes one or moreadditives and a solvent.

In some embodiments, the additive may be added to the fertilizer as adiscrete microencapsulated liquid, powder or granule. The encapsulationlayer containing the additive may be dissolve upon thermal or aqueousprocessing according to one embodiment. In some embodiments, theadditive may be encapsulated before it is added to the fertilizer. Insome embodiments, encapsulating the additive in a water-soluble coatingprevents the additive from being prematurely released or reacted priorto someone subjecting the fertilizer to aqueous-based furtherprocessing. Examples of suitable water-soluble coating materials includegelatins and cellulosic materials.

Encapsulation is a process in which tiny particles or droplets aresurrounded by a coating to give small capsules many useful properties.In a relatively simplistic form, a microcapsule is a small sphere with auniform wall around it, although many microcapsules have a non-sphericalcore that may be a crystal, a jagged adsorbent particle, an emulsion, asuspension of solids, or a suspension of smaller microcapsules. Mostmicrocapsules have diameters between a few micrometers and a fewmillimeters.

There are a number of different processes that can be used formicroencapsulation. These processes include but are not limited to pancoating, air-suspension coating, centrifugal extrusion, core-shellencapsulation, spray-drying and a variety of chemical processes.

When additives are added in a post-manufacture process, the additivescan be applied directly to a fertilizer product. In such processes,manufactured fertilizer products can be provided from one or moresources, and can be treated in order to add the additives. In someembodiments, the additives are provided in an additive mixture thatincludes an additive and a solvent. Additive mixtures can include one ormore additives, and can include any suitable combination of additivesfor the intended application.

Accordingly, one example of a method for adding a tracer to a fertilizercan include providing an additive mixture and applying the mixture to afertilizer to form a treated fertilizer product. The additive mixturecan include at least one additive, and may also include a solvent. Inone example, application of the additive mixture can include sprayingthe additive mixture onto the fertilizer product. The step of applyingthe additive mixture to the fertilize product can include combining theadditive mixture and the fertilizer product, and mixing the additivemixture with the fertilizer product. Mixing can be accomplished in anysuitable manner, including but not limited to stirring or agitating.Additional processing steps can also be used, such as, for example,drying of the treated fertilizer product after the additive has beenapplied.

In examples where the fertilizer product is a porous solid, the solventmay impart fluid and surface properties that allow the additive topenetrate into the fertilizer product. For example, the additive can beincorporated into the fertilizer product by physical absorption of theadditive into the porous solid material of the fertilizer product.

In examples where the additive includes a coating, the coating materialmay be a liquid including the additive and a suitable solvent.Alternatively, a coating process such as described in U.S. Pat. No.7,785,387, which is incorporated by reference in its entirety, may beemployed. As described in the '387 patent, fertilizer granules are firstcoated with a dispersant material and then an overcoating material. Forpurposes of the present invention, the dispersant material could includethe at least one additive described herein alone or in combination withan anti-caking material such as Zeolex 80, which is a sodium aluminumsilicate powder. The overcoating material may include conventionaldissolvable coatings such as wax, anti-caking material, water solublematerials and the like

In some embodiments, the additives may be in powder or wax form and maybe dissolved in at least one solvent in order to formulate theparticular compound, prepare the compound for the application, or impartadditional chemical properties to the compound. For example, a solventor solvents may be utilized to impart a rougher or porous surface to thefertilizer granules, in order to naturally hold more of the appliedadditive.

Contemplated solvents include any suitable pure or mixture of organicmolecules that are volatilized at a desired temperature. The solvent mayinclude any suitable pure or mixture of polar and non-polar compounds.As used herein, the term “pure” means that component that has a constantcomposition. As used herein, the term “mixture” means that componentthat is not pure, including salt water. As used herein, the term “polar”means that characteristic of a molecule or compound that creates anunequal charge, partial charge or spontaneous charge distribution at onepoint of or along the molecule or compound. As used herein, the term“non-polar” means that characteristic of a molecule or compound thatcreates an equal charge, partial charge or spontaneous chargedistribution at one point of or along the molecule or compound.

In some embodiments, the solvent or solvent mixture includes hydrocarbonsolvents. While a majority of hydrocarbon solvents are non-polar, thereare a few hydrocarbon solvents that could be considered polar.Hydrocarbon solvents are generally broken down into three classes:aliphatic, cyclic and aromatic. Aliphatic hydrocarbon solvents mayinclude both straight-chain compounds and compounds that are branchedand possibly crosslinked, however, aliphatic hydrocarbon solvents arenot considered cyclic. Cyclic hydrocarbon solvents are those solventsthat include at least three carbon atoms oriented in a ring structurewith properties similar to aliphatic hydrocarbon solvents. Aromatichydrocarbon solvents are those solvents that include generally three ormore unsaturated bonds with a single ring or multiple rings attached bya common bond and/or multiple rings fused together.

Examples of hydrocarbon solvents include toluene, xylene, p-xylene,m-xylene, mesitylene, solvent naphtha H, solvent naphtha A, alkanes,such as pentane, hexane, isohexane, heptane, nonane, octane, dodecane,2-methylbutane, hexadecane, tridecane, pentadecane, cyclopentane,2,2,4-trimethylpentane, petroleum ethers halogenated hydrocarbons, suchas chlorinated hydrocarbons, nitrated hydrocarbons, benzene,1,2-dimethylbenzene, 2,4-trimethylbenzene, mineral spirits, kerosine,isobutylbenzene, methylnaphthatenes, ethyltouene, and igroine.

In other embodiments, the solvent or solvent mixture may include othersolvents including ketones, such as acetone, diethyl ketone, methylethyl ketone and the like, alcohols, esters, ethers and amines In yetother embodiments, the solvent or solvent mixture may include acombination of any of the solvents mentioned herein.

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. For example, while the embodiments described above refer toparticular features, the scope of this invention also includesembodiments having different combinations of features and embodimentsthat do not include all of the above described features.

The invention claimed is:
 1. A fertilizer composition comprising: afertilizer material; and at least one additive which, upon thermal orchemical processing of the fertilizer material to form an explosivematerial, provides a visual, olfactory or electronically detectableindicator that such thermal or chemical processing has occurred, whereinthe additive is encapsulated.
 2. The fertilizer composition of claim 1,wherein the fertilizer material comprises ammonium nitrate.
 3. Thefertilizer composition of claim 1, wherein the fertilizer materialcomprises an ammonium nitrate double salt.
 4. The fertilizer compositionof claim 1, wherein the fertilizer material comprises an ammoniumsulfate nitrate double salt.
 5. The fertilizer composition of claim 1,wherein the additive comprises a material that provides a visual signal.6. The fertilizer composition of claim 5, wherein the additive comprisesa pyrotechnic material, a smoke producing material or a vapor producingmaterial.
 7. The fertilizer composition of claim 1, wherein the additivecomprises a material that is detectable by an electronic detector. 8.The fertilizer composition of claim 1, comprising a plurality ofgranules.
 9. The fertilizer composition of claim 8, wherein the additiveis dispersed in the granules.
 10. The fertilizer composition of claim 8,wherein the additive comprises a granule coating.
 11. The fertilizercomposition of claim 1, comprising at least two additives, wherein oneadditive provides a visual indicator and one additive provides anolfactory indicator.
 12. The fertilizer composition of claim 1, whereinthe at least one additive comprises at least a first additive and asecond additive, wherein the first additive provides an indicator inresponse to chemical processing and the second additive provides anindicator in response to thermal processing.
 13. The fertilizercomposition of claim 1 further comprising at least a second additivethat inhibits thermal or chemical processing of the fertilizer materialto form an explosive material.
 14. The fertilizer composition of claim13 wherein the second additive comprises a halide, a transition metalion or a combination thereof.
 15. A fertilizer composition comprising: afertilizer material; and at least one additive which, upon thermal orchemical processing of the fertilizer material to form an explosivematerial, provides an olfactory signal that such thermal or chemicalprocessing has occurred.
 16. The fertilizer composition of claim 15,wherein the additive that provides an olfactory signal comprises amaterial that is detectable by a canine.
 17. The fertilizer compositionof claim 15, wherein the additive comprises a pheromone.
 18. Thefertilizer composition of claim 15, wherein the additive comprises atleast one thiol or mercaptan.
 19. The fertilizer composition of claim18, wherein the additive comprises t-butyl mercaptan.
 20. The fertilizercomposition of claim 15, wherein the additive is microencapsulated. 21.A method of making a fertilizer comprising combining a fertilizermaterial with at least one additive which, upon thermal or chemicalprocessing of the ammonium nitrate containing fertilizer to form anexplosive material, provides a visual, olfactory or electronic indicatorthat such thermal or chemical processing has occurred; wherein thefertilizer material comprises granules, the additive comprises discreteencapsulates and the combining step comprises mixing the granules andthe encapsulates.
 22. The method of claim 21, wherein the fertilizermaterial comprises ammonium nitrate.
 23. The method of claim 21, whereinthe fertilizer material comprises granules, the additive comprises acoating material and the combining step comprises coating the granuleswith the coating material.
 24. The method of claim 21, wherein combiningthe ammonium nitrate containing fertilizer material with the additivecomprises mixing the additive with a solvent to form an additive mixtureand combining the additive mixture with the ammonium nitrate containingfertilizer material.
 25. The method of claim 21, wherein the additivecomprises a material that provides an olfactory signal.